Honeycombs are extruded into fairly simple overall geometries (e.g., cylinders). Some application requirements may demand more complex shapes than can be achieved by extrusion while still retaining the extruded cellular structure. Bonding together of extruded components after sintering can cause distortion of the thin wall cells by heating during joining processes such as brazing and welding. Bonding of components during sintering through the use of a paste or slurry applied to cellular surfaces can smear cell terminations and block free flow through joined cells. Paste or slurry is good for joining solid components, like electrodes, to cellular parts, but is less useful for joining honeycombs together.
Metal honeycombs are used for automotive exhaust pollution reduction. The effective surface area of the metal honeycomb, and therefore, its catalytic activity can be increased by producing a tortuous flow path for the exhaust gas which passes through the honeycomb. Various methods are used to increase flow path length. One such method is a "herringbone" pattern impressed into the surface of metal sheets used for foil honeycombs.
It would be advantageous to have a method of joining of cellular parts during sintering which does not require the use of a joining substance. Since extruded metal honeycombs are now used in catalytic applications, it would be advantageous to have a method of increasing the flow path length and varying flow path configurations of such honeycombs.
The present invention provides a method for achieving the above.